Method and apparatus for spinning artificial filaments



April 28, 1954 A. R. TOMLINSON 3,130,448

METHOD AND APPARATUS FOR SPINNING ARTIFICIAL FILAMENTS Filed May 11, 1961 United States Patent 3,130,448 IWETHGD AND APPARATUS FOR SPG ARTIFICIAL FILAREENTS Arthur R. Tomlinson, Garden City, Pa., assignor, by mesne assignments, to EMC Corporation, San Jose, Caliii, a corporation of Delaware Filed May 11, 196i, Ser. No. 169,313 5 Claims. (6!. 18-8) This invention relates to the production of artificial filaments and particularly to an improved method and apparatus for blending of filament-forming materials prior to shaping of the same.

Briefly, in conventional multi-filament spinning operation, using for example known melt spinning apparatus, a metered stream of molten filament-forming material is passed through a screen pack, breaker plate and into a multi-orificed spinneret where it is shaped into a plurality of individual streams. It has been found, however, that channels of high and low velocity flow exist within the stream of filament-forming material delivered to the spinneret, and that such flow channels persist even after passing through the screen pack and breaker plate. The presence of such channels of high and low velocity flow are particularly noticeable when the stream of filament-forming material undergoes a change in direction during its travel to the spinneret, and is especially pronounced when spinning a filament-forming material having a high melt viscosity. In view of the diiierences in the velocity of flow of the various portions of the filament-forming material, the flow rates of the filament-forming material extruded through the spinneret orifices also differ, with actual measurements indicating a variation from orifice to orifice of as much as i25%. As a result, the filaments of multifilament yarns produced by conventional spinning procedures vary considerably from each other in diameter. Accordingly, the primary object is to provide a new or improved and more satisfactory method and apparatus for use in the production of multi-filament yarns.

Another object is to provide an improved method and apparatus for multi-filament spinning operations wherein filament-forming material is blended just prior to shaping of the same so as to provide all portions thereof with substantially the same flow velocity.

Still another object is to provide a multi-filament spinning apparatus having means for blending different parts of a single stream of filament-forming material with each other as such stream is advanced toward a filament shaping device.

A further object is to provide an improved method and apparatus wherein a metered amount of pigment concentrate is injected into a stream of filament-forming material and uniformly blended therewith as such stream is advanced toward a filament shaping device.

These and other objects and advantages of the invention will be apparent from the following description and accompanying drawing in which:

FIGURE 1 is a vertical section through a portion of the apparatus of the present invention;

FIGURE 2 is a side view of one element of the apparatus shown in FIGURE 1; and

FIGURE 3 is a top view of the element shown in FIGURE 2.

The present invention is directed to melt spinning of multi-filament yarns, and more particularly to a method and apparatus for forming yarns comprised of a plurality of simultaneously shaped filaments which are substantially the same in cross-section and color uniformity. In general, the objects of this invention are achieved by dividing a single stream of molten filament-forming material into a plurality of corresponding individual streams which are caused to move along confined and intersecting paths which lead to a multi-orifice spinneret where they are again combined into a single main stream before being shaped into filaments. As the individual streams of filamerit-forming material cross with each other, portions of the material from each stream are mixed together. As a result, channels of high and low velocity flow which may have been present at different parts of the single stream of filament-forming material initially delivered are thoroughly blended so that all portions of the main stream of filament-forming material entering the spinneret flow at substantially the same velocity.

In lieu of or in addition to eliminating fiow differences within a stream of filament-forming material, the method and apparatus of the present invention may be employed for uniformly blending one or more pigments with the stream of filament-forming material as such stream travels toward a filament shaping device.

For the sake of simplicity, the method and apparatus of this invention are hereafter described as being employed in the manufacture of multi-filarnent yarns from polymers of propylene. It will be understood, however, that the teachings of the present invention may be employed with other filament-forming materials with equally satisfactory results.

With reference to the accompanying drawing, the apparatus of the present invention includes a conventional extrusion apparatus 15, a metering pump 17 carried by an extrusion block 19 in position for receiving molten polymer from the extrusion apparatus 15, a blending unit 21 for mixing the metered stream of molten polymer delivered by the pump 17, and an extrusion assembly, indicated generally at 23, for shaping the blended stream of molten polymer into filaments.

As heretofore mentioned, the extrusion apparatus 15 is of known construction and includes a barrel 25 into which are fed chips or pellets of propylene polymer, a rotatable screw conveyor 27 mounted within the barrel 25 for advancing the polymer therethrough, and heaters, such as shown at 29, which encase the barrel 25 and serve to heat and maintain the polymer at a desired elevated temperature, preferably ranging from 225 to 250 C.

The helical configuration of the screw conveyor 27 provides for a frequent and intimate contact of the polymer with the heated surfaces of the barrel 25, in addition to homogenizing the polymer and forcing air and other gases therefrom by compressing the same as it is converted to a molten condition. Preferably, the helical surface of the screw conveyor 27 is of reduced pitch along that portion which is adjacent to the discharge end of the barrel 25 to further compact the molten polymer to a ratio of about 4 to 1 and deliver the same to the pump 17 under a generally uniform pressure ranging from about 500 to 1500 psi. (pounds per square inch) through a passage 31 in the extrusion block 19.

In commercial operations the extrusion block passage 31 would preferably connect with a header having a series of pumps for delivering a metered amount of molten polymer to a plurality of individual blending units and xtrusion assemblies. For the sake of simplicity and ease of description, however, the apparatus illustrated includes only a single metering pump 17 having inlet and outlet ports 33 and 35 aligned with passages 31 and 37, respectively, in the extrusion block 19. The pump 17 is formed of heat-resistant materials to insure uniform and accurate operation at high temperatures and, as with con- I ventional metering pumps, includes a pair of meshing gears From the extrusion block passage 37 the metered flow of molten polymer passes through a connecting passage 39 and is delivered to the extrusion assembly 23, which includes a housing 41 removably carried by the extrusion block 19, a multi-orifice spinneret 43 secured to the housing 41 by an annular retainer 45, and a breaker plate 47 supported above the spinneret 43 by a spacer ring 49. A heater 51 is preferably provided for maintaining the polymer at a desired uniform temperature just prior to extrusion and extends well below the spinneret face to provide a heated zone, such as indicated at 53, within which the extruded filaments may be elongated by stretching forces applied by conventional take-up means, not shown. As the streams of filamentary material travel away from the extrusion assembly, they are quenched by suitable means, and preferably with a minimum of turbulence, as for example, by a continuous cross-flow of air supplied through a screened duct as shown at 55.

As heretofore mentioned, channels of high and low velocity flow are usually created within the stream of molten polymer as it undergoes a direction change during its travel from the metering pump to the extrusion assembly. With conventional melt extrusion apparatus, such channel flow is evidenced in the finished yarn which includes filaments of different diameters.

In accordance with the present invention flow differences within the polymer stream are eliminated by the unit 21 which serves to blend different portions of the stream together as it travels toward the extrusion assembly. As illustrated, the blending unit 21 is located within the extrusion block passage 3% and a connecting passage 57 in the housing 41 aligned therewith, and is supported above the breaker plate 47 by any suitable means, as for example by a pin 59. The blending unit 21 is of cylindrical shape which fits snugly within the aligned passages 39 and 57 and is provided on its surface with a plurality of helical grooves 61 and 63 which intersect with similar helical grooves 65 and 67 of equal but opposite pitch or hand. Thus, as the metered stream of molten polymer enters the extrusion block passage 39, it is divided into a plurality of individual streams which flow along confined paths as defined by the respective helical grooves 61, 63, 65, and 67. At the locations at which the right-handed and left-handed helical grooves intersect, portions of each polymer stream are carried into the path of the intersecting polymer stream so that repeated blending of the polymer streams is effected. Upon leaving the helical grooves of the blending unit 21, the individual, but now blended streams of molten polymer are again combined into a single main stream, in which all portions of the polymer fiow at substantially the same velocity.

The number, size and pitch of the helical grooves provided in the blending unit 21 may be varied from that illustrated on the drawing to satisfy particular operating conditions. It is preferred that the number and characeristics of the helical grooves provided be such as to facilitate the passage of the metered stream of molten polymer delivered by the pump 17 without substantial change in pressure. Further, to insure uniform blending of all portions of the stream of molten polymer, an equal number of grooves of like dimensions and equal but pposite pitch or hand should be provided, with the entrance and exit of the respective grooves being preferably located in diametrically opposed positions.

In addition to insuring that all portions of the molten polymer flow at substantially the same velocity during shaping of the same, the method and apparatus of the present invention may be also employed for securing uniform blending of a pigment with the molten polymer in the manufacture of color multi-filament yarns. Thus, as shown in FIGURE 1 of the drawing one or more streams of pigment may be delivered through a conduit 69 and injected into the stream of molten polymer as it enters the extrusion block passage 39. In a manner as described above, the combined pigment and polymer streams undergo repeated mixing as they fiow along the helical grooves of the blending unit 21 whereby all portions of the stream of polymer delivered to the spinneret are substantially the same, both in color and flow velocity.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. Apparatus for melt-spinning of multi-filament yarns including means for rendering thermoplastic polymeric filament-forming material molten, means for shaping the molten polymeric material into a plurality of filaments, walls defining a passage for conducting the molten polymeric material to said shaping means, a pump for delivering the molten polymeric material from said melting means to said passage, and a blending unit seated within said passage and snugly engaging with the walls thereof, said unit having an equal number of right-handed and left-handed intersecting helical grooves extending along its outer surface, said grooves being substantially the same in cross section and length whereby the metered stream of molten polymeric material is divided into a plurality of like individual streams which are blended together as they travel along said intersecting grooves.

2. Apparatus for making multi-filament yarns comprising means including a pump for delivering a metered stream of filament-forming material, means for shaping the delivered filament-forming material into a plurality of filaments, walls defining a passage for conducting the stream of filament-forming material from said pump and to said shaping means, and a blending unit seated within said passage and snugly engaged with the walls thereof, said blending unit including along its outer periphery a first group of helical grooves which are of substantially the same pitch, a second group of helical grooves which re of substantially the same pitch and which intersect with the first group of helical rooves, the helical grooves of said first and second groups of helical grooves having substantially like dimensions and being of opposite pitch whereby the metered stream of filament-forming material is divided into a plurality of individual streams which are blended together as they travel along said intersecting grooves.

3. A method for making multi-filament yarns includ ing the steps of delivering a metered stream of filamentforming material under pressure, separating the metered stream of filament-forming material into a plurality of individual streams, directing the individual streams of lament-forming material along an equal number of corresponding right-handed and left-handed intersecting helical paths which are of substantially the same pitch whereby portions of the individual streams are blended with each other, combining the individual blended streams of filament-forming material into a single stream and shaping the single stream of filament-forming material into a plurality of filaments.

4. A method for making multi-filament yarns including the steps of delivering a metered stream of filamentforming material under pressure, separating the metered stream of filament-forming material into a plurality of individual streams, blend ng portions of the individual streams of filament-forming material with each other by directing the same along an equal number of right-handed and left-handed intersecting helical paths which are of substantially the same dimensions and pitch, combining the blended individual streams of filament-forming material into a single stream and shaping the single stream of filament-forming material into a plurality of filaments.

5. A method of melt spinning of multi-filament yarns from a polymeric filament-forming material including the steps of delivering a metered stream of molten polymeric material under pressure, separating the metered stream of molten polymeric material into a plurality of individual streams, directing one-half of the individual streams of polymeric material along a first group of like helical stream of molten polymeric material into a plurality of paths which are of substantially the same pitch, directing filaments. the remainder of such individual streams of polymeric References Cited in the file of this patent material along a second group of like helical paths Which are of substantially the same pitch and which intersect 5 UNITED STATES PATENTS with the first group of helical paths whereby portions of 2,328,125 Buchsbaum et a1 Aug. 31, 1943 the different intersecting streams are blended together, 2,669,750 Keeney Feb. 23, 1954 combining the individual streams of blended molten oly- 2,801,440 Bauer Aug. 6, 1957 meric material into a single stream and shaping the single 2,947,598 Mafagliano et g- 2, 1960 

1. APPARATUS FOR MELT-SPINNING OF MULTI-FILAMENT YARNS INCLUDING MEANS FOR RENDERING THERMOPLASTIC POLYMERIC FILAMENT-FORMING MATERIAL MOLTEN, MEANS FOR SHAPING THE MOLTEN POLYMERIC MATERIAL INTO A PLURALITY OF FILAMENTS, WALLS DEFINING A PASSAGE FOR CONDUCTING THE MOLTEN POLYMERIC MATERIAL TO SAID SHAPING MEANS, A PUMP FOR DELIVERING THE MOLTEN POLYMERIC MATERIAL FROM SAID MELTING MEANS TO SAID PASSAGE, AND A BLENDING UNIT SEATED WITHIN SAID PASSAGE AND SNUGLY ENGAGING WITH THE WALLS THEREOF, SAID UNIT HAVING AN EQUAL NUMBER OF RIGHT-HANDED AND LEFT-HANDED INTERSECTING HELICAL GROOVES EXTENDING ALONG ITS OUTER SURFACE, SAID GROOVES BEING SUBSTANTIALLY THE SAME IN CROSS SECTION AND LENGTH WHEREBY THE METERED STREAM OF MOLTEN POLYMERIC MATERIAL IS DIVIDED INTO A PLURALITY OF LIKE INDIVIDUAL STREAMS WHICH ARE BLENDED TOGETHER AS THEY TRAVEL ALONG SAID INTERSECTING GROOVES. 